TWI587557B - Light-emitting element, light-emitting device, display device, electronic appliance, and lighting device - Google Patents

Description

Light-emitting element, light-emitting device, display device, electronic device and lighting device

The present invention relates to a light-emitting element, a display device, a light-emitting device, an electronic device, and a lighting device using an organic compound as a light-emitting substance.

In recent years, research and development of light-emitting elements (organic EL elements) using organic electroluminescence (EL: Electroluminescence) using a compound have become increasingly hot. In the basic structure of these light-emitting elements, an organic compound layer (EL layer) containing a light-emitting substance is interposed between a pair of electrodes. Luminescence from the luminescent material can be obtained by applying a voltage to the above elements.

Since such a light-emitting element is a self-luminous type light-emitting element, it has advantages superior to those of a liquid crystal display such as high visibility of a pixel, and no backlight or the like is required, and thus such a light-emitting element is considered to be suitable for a flat panel display element. In addition, a display using such a light-emitting element can be made thin and light, which is also an enormous advantage. Furthermore, the very fast response speed is also one of the features.

Because the luminescent layer of such a luminescent element can be continuously topographically oriented in two dimensions Into, so that surface luminescence can be obtained. Therefore, it is possible to easily form an element having a large area. Since this feature is difficult to obtain by a point light source typified by an incandescent lamp or an LED or a line light source typified by a fluorescent lamp, the use value of the above-described light-emitting element is high as a surface light source applicable to illumination or the like. .

In order to use the light-emitting element as illumination, it is important to obtain white light. In general, white light emission can be obtained by applying a multicolor light-emitting element that emits light that is synthesized from a plurality of light-emitting center materials having different emission spectra.

Although Patent Document 1 discloses a structure in which a layer for adjusting a color is provided in a light-emitting element in which a plurality of light-emitting layers are laminated, a constituent element is added when the structure is employed, so that in terms of cost, unfavorable.

[Patent Document 1] Japanese Patent Application Publication No. 2010-033780

In the above-described multicolor light-emitting element, simultaneously obtaining light emission of different wavelengths means that light emission by different energy levels is simultaneously obtained. However, light of different energy levels must have a level of energy level, thereby making it possible to generate energy transfer.

Thus, when the above-described elements are used to obtain a desired luminescent color, a precise component design in consideration of energy transfer is required, but it takes a long time and a lot of manpower if the design is performed.

Accordingly, an object of the present invention is to provide a multi-color light-emitting element in which light-emitting layers of different light-emitting colors are stacked, and the multi-color light-emitting element is easy to adjust Colored light-emitting elements.

Further, another object of the present invention is to provide a multicolor light-emitting element which is inexpensive and has excellent light-emitting efficiency.

Further, another object of the present invention is to provide a multicolor light-emitting element which is easy to adjust color and has low luminous efficiency.

Further, another object of the present invention is to provide a light-emitting device, a display device, an electronic device, and a lighting device which can be manufactured at low cost by using the above-described light-emitting elements.

Further, another object of the present invention is to provide a light-emitting device, a display device, an electronic device, and a lighting device in which power consumption is reduced by using the above-described light-emitting elements.

The present invention is only required to solve any of the above problems.

In the light-emitting element in which at least two light-emitting layers emitting different light-emitting colors are formed in contact, light from the light-emitting layer of the exciplex is obtained, and thus the above problem can be solved.

That is, one of the structures of the present invention is a light-emitting element including a first electrode, a second electrode, and an EL layer sandwiched between the first electrode and the second electrode, the EL layer including at least a laminate a light emitting layer of the first light emitting layer and the second light emitting layer, the first light emitting layer comprising a first organic compound and a second organic compound, the second light emitting layer comprising a third organic compound and a fourth organic compound, the first organic compound The combination with the second organic compound forms a first excimer complex, and the combination of the third organic compound and the fourth organic compound forms a second exciplex.

A light-emitting element using a general luminescent substance that is not an exciplex In the present case, the band gap or the triplet energy level causes energy transfer between the luminescent substances, between the host substances, and between the luminescent substance and the host substance, thereby causing the luminescence to be obtained in the plurality of luminescent layers. Adjustment of components such as element structure or doping concentration becomes complicated. On the other hand, since the energy transfer is not easily generated between the excimers, the light emission from the two light-emitting layers can be obtained in the light-emitting element having the present structure.

In addition, the excimer complex is in a state in which the single-excitation energy level and the triple-excitation energy level are close to each other, so that it is easy to generate a reverse intersystem crossing from the triplet excited state to the singlet excited state, and is easily delayed. The state of light. The delayed fluorescence can convert the triplet excited state to the fluorescent light, thereby improving the luminous efficiency of the light emitting element. In order to exhibit delayed fluorescence with high efficiency, the difference between the triplet excited state and the singlet excited state is preferably 0.2 eV or less, more preferably 0.1 eV or less.

Thus, another structure of the present invention is a light-emitting element having the above structure, wherein the first excimer compound exhibits delayed fluorescence.

Further, another structure of the present invention is a light-emitting element having the above structure, wherein the second excimer compound exhibits delayed fluorescence.

Further, another structure of the present invention is a light-emitting element having the above structure, wherein both the first excimer and the second excimer are delayed fluorescent.

Further, another configuration of the present invention is a light-emitting element having the above structure and having an external quantum efficiency of 5% or more.

In addition, by forming a recombination region in each of the light-emitting elements The interface between the light layers allows the two light-emitting layers to emit light efficiently. One of the two substances by forming the exciplex is an electron transporting substance and the other is a material having hole transportability, thereby being advantageous in terms of forming an exciplex. Further, when one of the above substances is a substance having electron transporting property and the other is a substance having hole transporting property, the transportability of each of the light emitting layers can be easily controlled according to the mixing ratio of the two substances, and can be easily adjusted. Combine the area.

That is, another structure of the present invention is a light-emitting element having the above structure, wherein a recombination region of electrons and holes in the light-emitting layer is located at an interface between the first light-emitting layer and the second light-emitting layer.

Further, another structure of the present invention is the light-emitting element having the above structure, wherein one of the first organic compound and the second organic compound is a substance having electron transport property, and the other is a substance having hole transportability. One of the above third organic compound and the above fourth organic compound is a substance having electron transport property, and the other is a substance having hole transportability.

Further, another structure of the present invention is a light-emitting element having the above structure, wherein one of the first electrode and the second electrode functions as an anode, and the other serves as a cathode, and is used in the first light-emitting layer and the second light-emitting layer. One of the electrodes on the anode side of the anode contains a substance having a hole transporting property, and the other one of the first light-emitting layer and the second light-emitting layer on the side of the electrode serving as the cathode contains a substance having electron transportability. Contains more.

Further, since the light-emitting wavelengths of the respective exciplexes are different, the light-emitting element can be formed to exhibit a large color of light emitted from each of the excited complexes. The color-emitting light-emitting element can obtain white light by making the light-emitting light in a complementary color relationship.

That is, another structure of the present invention is a light-emitting element having the above structure, wherein the first excimer and the second excimer are light having peaks at different wavelengths.

Further, another structure of the present invention is a light-emitting element having the above structure, which has an emission spectrum of two peaks.

Further, another structure of the present invention is a light-emitting element having the above structure, which light-emitting element exhibits white light emission.

Further, the light emission wavelength of the excimer complex can also be changed by changing one of the two substances forming the exciplex. That is, one of the two substances forming the excimer complex can be used in common in the plurality of light-emitting layers, so that the components can be manufactured more inexpensively and easily by reducing the constituent elements.

That is, the other structure of the present invention is a light-emitting element having the above structure, wherein one of the first organic compound and the second organic compound is the same as one of the third organic compound and the fourth organic compound.

Further, another configuration of the present invention is a light-emitting module including a light-emitting element having the above configuration and a unit for controlling the light-emitting element.

Further, another configuration of the present invention is a display module in which a display portion includes a light-emitting element having the above-described configuration and the display module includes a unit that controls the light-emitting element.

Further, another structure of the present invention is a lighting device including the light-emitting element having the above structure.

Further, another configuration of the present invention is a light-emitting device including a light-emitting element having the above configuration and a unit for controlling the light-emitting element.

Further, another configuration of the present invention is a display device in which a display portion includes a light-emitting element having the above configuration and the display device includes a unit that controls the light-emitting element.

Further, another structure of the present invention is an electronic device including the light-emitting element having the above structure.

Note that the light-emitting device in this specification includes an image display device using a light-emitting element. In addition, for example, the following modules are included in the light-emitting device: the light-emitting element is mounted with a connector such as an anisotropic conductive film or a TCP (Tape Carrier Package) module; and a printed circuit board is disposed at the end of the TCP. A module in which an IC (integrated circuit) is directly mounted on a light-emitting element by a COG (Chip On Glass) method. Furthermore, the light-emitting device in the present specification further includes a light-emitting device for a lighting device or the like.

One aspect of the present invention can provide a multicolor light-emitting element in which light-emitting layers of different light-emitting colors are stacked, the multi-color light-emitting element being a light-emitting element that is easy to adjust color.

Further, another aspect of the present invention can provide a multicolor light-emitting element which is inexpensive and has excellent light-emitting efficiency.

Further, another aspect of the present invention can provide a multicolor light-emitting element which is easy to adjust color and which is excellent in luminous efficiency.

In addition, another aspect of the present invention can provide a light-emitting device, a display device, and an electric device which can be manufactured at low cost by using the above-described light-emitting elements. Sub-devices and lighting equipment.

Further, another aspect of the present invention can provide a light-emitting device, a display device, an electronic device, and a lighting device each having a reduced power consumption by using the above-described light-emitting elements.

101‧‧‧First electrode

102‧‧‧second electrode

103‧‧‧EL layer

111‧‧‧ hole injection layer

112‧‧‧ hole transport layer

113‧‧‧Lighting layer

113a‧‧‧First luminescent layer

113b‧‧‧second luminescent layer

114‧‧‧Electronic transport layer

115‧‧‧Electronic injection layer

400‧‧‧Substrate

401‧‧‧first electrode

403‧‧‧EL layer

404‧‧‧second electrode

405‧‧‧ Sealing material

406‧‧‧ Sealing material

407‧‧‧Seal substrate

412‧‧‧ pads

420‧‧‧ IC chip

601‧‧‧Drive circuit unit (source line drive circuit)

602‧‧‧Pixel Department

603‧‧‧Drive circuit unit (gate line drive circuit)

604‧‧‧Seal substrate

605‧‧‧ sealing material

607‧‧‧ Space

608‧‧‧Wiring

609‧‧‧FPC (Flexible Printed Circuit)

610‧‧‧ element substrate

611‧‧‧Switching TFT

612‧‧‧ Current Control TFT

613‧‧‧First electrode

614‧‧‧Insulators

616‧‧‧EL layer

617‧‧‧second electrode

618‧‧‧Lighting elements

623‧‧‧n channel type TFT

624‧‧‧p channel type TFT

625‧‧‧Drying agent

901‧‧‧Shell

902‧‧‧Liquid layer

903‧‧‧Backlight unit

904‧‧‧Shell

905‧‧‧Drive IC

906‧‧‧terminal

951‧‧‧Substrate

952‧‧‧electrode

953‧‧‧Insulation

954‧‧‧Isolation

955‧‧‧EL layer

956‧‧‧electrode

1001‧‧‧Substrate

1002‧‧‧Base insulating film

1003‧‧‧gate insulating film

1006‧‧‧gate electrode

1007‧‧‧gate electrode

1008‧‧‧gate electrode

1020‧‧‧First interlayer insulating film

1021‧‧‧Second interlayer insulating film

1022‧‧‧electrode

First electrode of 1024W‧‧‧ illuminating element

First electrode of 1024R‧‧‧ illuminating element

First electrode of 1024G‧‧‧ illuminating element

The first electrode of the 1024B‧‧‧ illuminating element

1025‧‧‧ partition wall

1028‧‧‧EL layer

1029‧‧‧Second electrode of the light-emitting element

1031‧‧‧Seal substrate

1032‧‧‧ Sealing material

1033‧‧‧ Transparent substrate

1034R‧‧‧Red colored layer

1034G‧‧‧Green color layer

1034B‧‧‧Blue color layer

1035‧‧‧Black layer (black matrix)

1036‧‧‧ Coverage

1037‧‧‧ Third interlayer insulating film

1040‧‧‧Pixel Department

1041‧‧‧Drive Circuit Division

1042‧‧‧The surrounding department

2001‧‧‧Shell

2002‧‧‧Light source

3001‧‧‧Lighting equipment

5000‧‧‧Display area

5001‧‧‧Display area

5002‧‧‧Display area

5003‧‧‧Display area

5004‧‧‧Display area

5005‧‧‧Display area

7101‧‧‧Shell

7103‧‧‧Display Department

7105‧‧‧ bracket

7107‧‧‧Display Department

7109‧‧‧ operation keys

7110‧‧‧Remote control

7201‧‧‧ Subject

7202‧‧‧ Shell

7203‧‧‧Display Department

7204‧‧‧ keyboard

7205‧‧‧External connection埠

7206‧‧‧ pointing device

7210‧‧‧Second display

7301‧‧‧Shell

7302‧‧‧Shell

7303‧‧‧Connected section

7304‧‧‧Display Department

7305‧‧‧Display Department

7306‧‧‧Speaker Department

7307‧‧‧Storage media insertion

7308‧‧‧LED lights

7309‧‧‧ operation keys

7310‧‧‧Connecting terminal

7311‧‧‧Sensor

7401‧‧‧ Shell

7402‧‧‧Display Department

7403‧‧‧ operation button

7404‧‧‧External connection埠

7405‧‧‧Speakers

7406‧‧‧Microphone

7400‧‧‧Mobile Phone

9033‧‧‧ clip

9034‧‧‧Switch

9035‧‧‧Power switch

9036‧‧‧ switch

9038‧‧‧Operation switch

9630‧‧‧Shell

9631‧‧‧Display Department

9631a‧‧‧Display Department

9631b‧‧‧Display Department

9632a‧‧‧Touch screen area

9632b‧‧‧Touch screen area

9633‧‧‧Solar battery

9634‧‧‧Charge and discharge control circuit

9635‧‧‧Battery

9636‧‧‧DCDC converter

9637‧‧‧ operation keys

9638‧‧‧ converter

9639‧‧‧ button

In the drawings: FIG. 1 is a schematic view of a light-emitting element; FIGS. 2A and 2B are schematic views of an active matrix type light-emitting device; FIGS. 3A and 3B are schematic views of a passive matrix-type light-emitting device; and FIG. 4 is a schematic view of an active matrix type light-emitting device; 5A and 5B are schematic views of an active matrix type light-emitting device; FIGS. 6A and 6B are schematic views showing a lighting device; FIGS. 7A, 7B1 and 7B2, 7C, and 7D are views showing an electronic device; and FIG. 8 is a view showing an electronic device; FIG. 9 is a view showing a lighting device; FIG. 10 is a view showing the lighting device; FIG. 11 is a view showing the in-vehicle display device and the lighting device; and FIGS. 12A to 12C are views showing the electronic device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and those skilled in the art to which the present invention pertains can easily understand that the fact is the manner The details can be changed into various forms without departing from the spirit and scope of the invention. Therefore, the present invention should not be construed as being limited to the contents described in the embodiments shown below.

Embodiment 1

As a multicolor light-emitting element that obtains light from a plurality of light-emitting substances, a light-emitting element in which one light-emitting layer includes a plurality of light-emitting center materials, a light-emitting element in which light-emitting layers including different light-emitting center substances are laminated, and an intermediate layer are disposed A light-emitting element between light-emitting layers comprising different luminescent center materials.

It is known that in an element other than the element using the intermediate layer in the above-mentioned light-emitting element, energy transfer occurs between the light-emitting center materials directly or by the host material, thereby greatly affecting luminous efficiency or color of light emission. .

Although the above energy transfer is controlled depending on the element structure, the selection of the host material or the luminescent center substance, the presence or absence of the additive, or the amount of the additive, a lot of labor is required when controlling the energy transfer.

In addition, the element using the intermediate layer has disadvantages in that the number of layers formed is increased and the cost is increased; the driving voltage is increased, and the like.

Thus, one aspect of the present invention provides a multicolor light-emitting element in which a first light-emitting layer and a second light-emitting layer are laminated, light of different wavelengths is from the first light-emitting layer and the second light-emitting layer, and the image is obtained from synthesis Light of different wavelengths. Light from the luminescent layer is derived from the exciplex.

Fig. 1 shows a schematic view of a light-emitting element of the present embodiment. Present implementer The light-emitting element of the formula has a structure in which the EL layer 103 is sandwiched between the first electrode 101 and the second electrode 102. One of the first electrode 101 and the second electrode 102 serves as an anode and the other serves as a cathode. A case where the first electrode 101 functions as an anode and the second electrode 102 functions as a cathode will be described in FIG.

The EL layer 103 includes at least the light emitting layer 113. The other layers in the EL layer 103 are not particularly limited. For example, as shown in FIG. 1, the EL layer 103 further includes a hole injection layer 111, a hole transport layer 112, an electron transport layer 114, an electron injection layer 115, and the like.

The light emitting layer 113 is composed of a first light emitting layer 113a and a second light emitting layer 113b. The first light-emitting layer 113a includes at least a first organic compound and a second organic compound, and the second light-emitting layer 113b contains at least a third organic compound and a fourth organic compound. In addition, the first light-emitting layer 113a may also contain only the first organic compound and the second organic compound. Similarly, the second light-emitting layer 113b may also contain only the third organic compound and the fourth organic compound.

Here, the exciplex is in an excited state composed of two substances. For example, in the case of photoexcitation, the exciplex is formed by extracting one of the other substances in the ground state by one molecule in an excited state. Thus, when the light is in the ground state, the exciplex is restored to the original impurity. Thus, there is no ground state as an excimer complex, and in principle, energy transfer to the exciplex is unlikely to occur. Thereby, the light-emitting element of the present embodiment which suppresses energy transfer between the light-emitting layers does not need to adjust a complicated element structure due to energy transfer, and it is possible to easily obtain desired light emission from the two light-emitting layers.

As described above, the exciplex is composed of two organic compounds. Thereby, the first light-emitting layer 113a includes at least a first organic compound and a second organic compound, and the second light-emitting layer 113b contains at least a third organic compound and a fourth organic compound. Further, the combination of the first organic compound and the second organic compound and the combination of the third organic compound and the fourth organic compound all form at least an exciplex.

As a combination of the above two organic compounds, it is preferred that one of the above two organic compounds is a compound which is easy to accept electrons (a material having electron transport property), and the other is a compound which easily accepts a hole (having a hole) A combination of transportable materials) because the combination facilitates the formation of excimer complexes.

Further, by using a material having electron transportability as one of the above two organic compounds, and using a material having hole transportability as another, and by adjusting the content ratio in the light-emitting layer, the light-emitting layer can be easily controlled. The load of 113 is balanced.

The light-emitting element of the present embodiment can equally distribute excitation energy to the first light-emitting layer 113a and the second by forming a recombination region of the carrier in the vicinity of the interface between the first light-emitting layer 113a and the second light-emitting layer 113b. The light-emitting layer 113b can thereby obtain light emission from each light-emitting layer without any effort. In addition, as described above, the combination of the first organic compound to the fourth organic compound is set as a compound (electron transporting material) that easily accepts electrons and a compound (material having hole transporting property) that is easy to receive holes. By combining, and by adjusting the mixing ratio, it is possible to easily arrange the recombination region between the first light-emitting layer 113a and the second light-emitting layer 113b. The way around the interface is adjusted. Further, by changing the position of the recombination region, it is also possible to control the emission intensity from each of the light-emitting layers, so that the emission spectrum of the light-emitting element can be easily adjusted. In order to form a recombination region of the carrier in the vicinity of the interface between the first luminescent layer 113a and the second luminescent layer 113b, one of the first luminescent layer 113a and the second luminescent layer 113b near the anode has a hole transmission The one of the first light-emitting layer 113a and the second light-emitting layer 113b which is close to the cathode is a layer having electron transportability. Further, the layer having hole transportability may include a material having a hole transporting property, and a layer having electron transport properties may also contain a material having electron transport properties.

The excimer complex exhibits luminescence: a HOMO energy level derived from a shallower side (smaller absolute value) and a LUMO energy level on a deeper side (larger absolute value) of the two substances forming the exciplex. The difference between the energy of the luminescence. Thus, in the combination of the first organic compound and the second organic compound and the combination of the third organic compound and the fourth organic compound, even if one substance is the same substance, it can be obtained from the first light-emitting layer and the second light-emitting layer. Luminescence of different wavelengths. By using one of the substances forming the excimer complex in the first light-emitting layer and the second light-emitting layer, the kind of the material constituting the light-emitting element is reduced, so that the light-emitting element can be manufactured more inexpensively and easily, and can be realized. Suitable for mass production of light-emitting elements. In addition, the interface between the first luminescent layer and the second luminescent layer reduces the implantation barrier of the carrier, whereby this also contributes to the long lifetime of the component.

Here, as the excited state formed by the organic compound, a singlet excited state and a triplet excited state are exemplified, and the luminescence from the singlet excited state (S ₁ ) is called fluorescence, and the triplet excited state (T ₁ ) Luminescence is called phosphorescence. Further, in the light-emitting element, the statistically generated ratio of the singlet excited state to the triplet excited state is considered to be S ₁ : T ₁ = 1:3. Thus, a light-emitting element using a phosphorescent compound capable of converting a triplet excited state to light emission can achieve higher light-emitting efficiency than a light-emitting element using a fluorescent compound, and thus development of a light-emitting element using a phosphorescent compound has been increasingly developed in recent years. fiery.

On the other hand, however, most of the phosphorescent compounds currently used are complexes in which a rare metal such as ruthenium is a central metal, which may be expensive and unstable in supply.

As the light-emitting means capable of converting the triplet excitation energy into light, the phosphorescence is delayed fluorescent. The mechanism is a structure that exhibits luminescence by upconverting the triplet excited state to a singlet excited state by generating an inverse intersystem crossing. Fluorescence can also be obtained by using delayed fluorescence, which can exceed 25% of the limit of the internal quantum efficiency considered to be fluorescent.

The closer the singlet excited state to the triplet excited state, the easier it is to generate the delayed fluorescence. The excimer complex is in a state in which the singlet excited state and the triplet excited state are close, so that delayed fluorescence is easily generated. The triplet excited state of the light-emitting element of the present embodiment can also contribute to light emission by using an excimer complex which efficiently generates delayed fluorescence, and can provide a light-emitting element having high light-emitting efficiency. Note that this delayed fluorescence also includes so-called Thermally Activated Delayed Fluorescence (TADF) which increases the efficiency of the reverse intersystem crossing due to how much heating (including its own heating). In addition, in order to efficiently exhibit delayed fluorescence, the energy difference between the singlet excited state and the triplet excited state is preferably 0 eV or more and 0.2 eV or less, more preferably The structure is such a structure that the energy difference is 0 eV or more and 0.1 eV or less.

Further, if one of the two light-emitting layers is a light-emitting layer exhibiting delayed fluorescence, an effect of improving luminous efficiency can be obtained, but it is more preferable to adopt a structure in which both of the light-emitting layers exhibit delayed fluorescence.

When a light-emitting element exhibiting delayed fluorescence is used, sometimes the external quantum efficiency exceeds 5% (the rate of generation of the single-excited state is 25% × the light extraction efficiency is 20%), that is, the fluorescent light-emitting element which hardly exhibits delayed fluorescence. The theoretical limit. In the light-emitting element having the structure of the light-emitting element of the present embodiment, a light-emitting element having an external quantum efficiency of more than 5% can be emitted as a light-emitting element that exhibits delayed fluorescence with high efficiency.

In addition, from another point of view, when the EL internal quantum yield Φe1 (= Φp × 25% (the production rate of the singlet excited state in EL)) estimated from the PL quantum yield Φp of the exciplex is higher than that of luminescence When the internal quantum yield Φe2 (external quantum yield ÷ 20% (light extraction efficiency)) of the element is small, it can be said that the delayed fluorescence is exhibited with high efficiency. When Φe2 is about twice as large as Φe1, the effect of using the light-emitting element of the present embodiment is further exhibited, so that the structure is a preferable structure.

The light-emitting element of the present embodiment having the above-described configuration may be a light-emitting element of multi-color light emission by obtaining light of an excimer from light rays exhibiting light emission of different light-emitting wavelengths in the first light-emitting layer and the second light-emitting layer. The emission spectrum of such a light-emitting element has at least two peaks.

In addition, even if the first light-emitting layer and the second light-emitting layer which are in contact with the topographical cost embodiment are not easily generated with energy transfer between the two light-emitting layers, a light-emitting element which easily adjusts the light-emission balance can be realized.

Therefore, the light-emitting element can be applied to a light-emitting element that exhibits white light emission, which is important for adjusting the light-emitting color, and is more suitable for a light-emitting element for illumination use.

By using an excimer as a light-emitting layer, the light-emitting element of the present embodiment having the above-described structure can achieve an energy transfer between the light-emitting layers, and it is easy to adjust the light-emitting color.

Further, since the light-emitting element of the present embodiment utilizes light emission from the excited complex, it is easy to exhibit delayed fluorescence. By using delayed fluorescence, triplet excitation energy can be converted to light emission, and a light-emitting element having high luminous efficiency can be realized.

Further, by using the excimer complex, energy transfer between the light-emitting layers is less likely to occur in the light-emitting element of the present embodiment, and delayed fluorescence is easily obtained. Thereby, it is possible to realize a light-emitting element which is easy to adjust the light-emitting color and has good light-emitting efficiency.

Embodiment 2

In the present embodiment, an example of the detailed configuration of the light-emitting element described in the first embodiment will be described below with reference to Fig. 1 .

The light-emitting element of the present embodiment includes an EL layer composed of a plurality of layers between a pair of electrodes. In the present embodiment, the light-emitting element is composed of the first electrode 101, the second electrode 102, and the EL layer 103 provided between the first electrode 101 and the second electrode 102. Note that in the present embodiment, the following description will be made assuming that the first electrode 101 functions as an anode and the second electrode 102 functions as a cathode. That is, when the potential of the first electrode 101 is higher than that of the second electrode When a voltage is applied to the first electrode 101 and the second electrode 102 in a manner of a potential of 102, light emission can be obtained.

Since the first electrode 101 is used as an anode, it is preferably formed using a metal having a large work function (specifically, 4.0 eV or more), an alloy, a conductive compound, a mixture thereof, or the like. Specifically, for example, indium oxide-tin oxide (ITO: indium tin oxide), indium oxide-tin oxide containing antimony or antimony oxide, indium oxide-zinc oxide, indium oxide containing tungsten oxide and zinc oxide (IWZO) )Wait. Although these conductive metal oxide films are usually formed by a sputtering method, they can also be produced by a sol-gel method or the like. As an example of the production method, a method of forming indium oxide-zinc oxide by a sputtering method using a target in which 1 wt% to 20 wt% of zinc oxide is added to indium oxide is used. In addition, indium oxide (IWZO) containing tungsten oxide and zinc oxide may be formed by a sputtering method using a target in which 0.5 wt% to 5 wt% of tungsten oxide and 0.1 wt% to 1 wt% of zinc oxide are added with respect to indium oxide. . Further, examples thereof include gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), and copper (Cu). Palladium (Pd) or a nitride of a metal material (for example, titanium nitride) or the like. Graphene can also be used. Further, by using a composite material to be described later for the layer in the EL layer 103 that is in contact with the first electrode 101, the electrode material can be selected regardless of the work function.

The laminated structure of the EL layer 103 is not particularly limited as long as it has the structure of the light-emitting layer 113 shown in Embodiment 1. For example, a stack of the EL layer 103 may be formed by appropriately combining a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, a carrier blocking layer, an intermediate layer, and the like. structure. In the present embodiment, the EL layer 103 includes a hole injection layer 111, a hole transport layer 112, a light-emitting layer 113, an electron transport layer 114, and an electron injection layer 115 which are sequentially stacked on the first electrode 101. Hereinafter, specific materials constituting each layer will be described.

The hole injection layer 111 is a layer containing a substance having high hole injectability. Further, molybdenum oxide, vanadium oxide, cerium oxide, tungsten oxide, manganese oxide or the like can be used. Further, a phthalocyanine-based compound such as phthalocyanine (abbreviation: H ₂ Pc), copper phthalocyanine (abbreviation: CuPc), or the like; an aromatic amine compound such as 4,4'-bis[ N- (4-diphenylamino) can also be used. Phenyl) -N -phenylamino]biphenyl (abbreviation: DPAB), N,N' -bis{4-[bis(3-methylphenyl)amino]phenyl}- N,N' -diphenyl Base-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD); or a polymer such as poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) PEDOT/PSS) or the like to form the hole injection layer 111.

Further, as the hole injection layer 111, a composite material containing an acceptor substance in a material having hole transport properties can be used. Note that by using a composite material containing an acceptor substance in a material having hole transportability, the material forming the electrode can be selected regardless of the work function of the electrode. That is, as the first electrode 101, a material having a small work function can be used in addition to a material having a large work function. Examples of the acceptor substance include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F ₄ -TCNQ), and chloranil. Further, examples thereof include transition metal oxides and oxides of metals belonging to Groups 4 to 8 of the periodic table. Specifically, vanadium oxide, cerium oxide, cerium oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, or cerium oxide is preferably used because of its high electron acceptability. It is particularly preferable to use molybdenum oxide because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle.

As the material having a hole transporting property for a composite material, various organic compounds such as an aromatic amine compound, a carbazole derivative, an aromatic hydrocarbon, a polymer compound (oligomer, dendrimer, polymer, etc.) and the like can be used. As the organic compound used for the composite material, an organic compound having high hole transport property is preferably used. Specifically, it is preferred to use a substance having a hole mobility of 10 ^-6 cm ² /Vs or more. Hereinafter, an organic compound which can be used as a material having hole transportability in a composite material is specifically exemplified.

For example, as the aromatic amine compound, N,N'-bis( p -tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4, 4'- may be mentioned. Bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino] Phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 1,3,5-tri[N-(4-di Phenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B) or the like.

As the carbazole derivative which can be used for the composite material, specifically, 3-[N-(9-phenyloxazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation) :PCzPCA1),3,6-bis[N-(9-phenyloxazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-( 1-Naphthyl)-N-(9-phenyloxazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1).

Further, as the carbazole derivative which can be used for the composite material, 4,4'-bis(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tri[4-( N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(10-phenyl-9-fluorenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 1,4- Bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene and the like.

Further, as the aromatic hydrocarbon which can be used for the composite material, for example, 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10 can be mentioned. -bis(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylbenzene Base) (abbreviation: t-BuDBA), 9,10-bis(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylhydrazine Abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA), 2-tert-butyl-9,10-bis[2-(1-naphthyl) Phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2 ,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9'-biindole, 10,10'-diphenyl-9,9'-linked, 10 , 10'-bis(2-phenylphenyl)-9,9'-biindole, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9, 9'- hydrazine, hydrazine, fused tetraphenyl, erythroprene, hydrazine, 2,5,8,11-tetra(tert-butyl)fluorene, and the like. In addition, pentacene, hydrazine, and the like can also be used. As such, it is preferred to use an aromatic hydrocarbon having 14 to 42 carbon atoms having a hole mobility of 1 × 10 ^-6 cm ² /Vs or more.

Note that the aromatic hydrocarbons that can be used in the composite material can also have a vinyl skeleton. Examples of the aromatic hydrocarbon having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) and 9,10-bis[4-(2,2-di). Phenylvinyl)phenyl]anthracene (abbreviation: DPVPA).

In addition, poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-( 4-Diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide [abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl) a polymer compound such as -N,N'-bis(phenyl)benzidine (abbreviation: Poly-TPD).

By forming the hole injection layer, the hole injectability is improved, and a light-emitting element having a small driving voltage can be obtained.

The hole transport layer 112 is a layer containing a material having hole transportability. As a material having hole transport, for example, an aromatic amine compound or the like such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N, N can be used. '-Bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4 "-Tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4"-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(spiro-9,9'-biguanidin-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl- 4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP). The substance described herein has high hole transportability, and the hole mobility is mainly 10 ^-6 cm ² /Vs or more. Further, an organic compound which is a material having a hole transporting property in the above composite material may be used for the hole transport layer 112. Further, a polymer compound such as poly(N-vinylcarbazole) (abbreviation: PVK) or poly(4-vinyltriphenylamine) (abbreviation: PVTPA) may also be used. Further, the layer including the material having the hole transport is not limited to a single layer, and may be a laminate of two or more layers composed of the above substances.

The light-emitting layer 113 has the structure of the light-emitting layer 113 described in the first embodiment. That is, the first light-emitting layer 113a and the second light-emitting layer 113b are laminated in this order from the first electrode side. In addition, the first light emitting layer 113a includes a first organic compound and a second organic compound, and the second light emitting layer 113b includes a third organic compound and a fourth organic compound. The light-emitting element of the present embodiment is characterized in that the combination of the first organic compound and the second organic compound forms the first An excimer complex, the combination of the third organic compound and the fourth organic compound forms a second exciplex. Further, the light-emitting element of the present embodiment has a structure for obtaining light emission from the first exciplex and the second exciplex.

The material which can be used as the first organic compound, the second organic compound, the third organic compound, and the fourth organic compound is not particularly limited as long as it satisfies the conditions shown in the first embodiment, and various carriers can be selected. Transfer material.

For example, as a material having electron transport property (a compound which is easy to accept electrons), bis(10-hydroxybenzo[h]quinoline) ruthenium (II) (abbreviation: BeBq ₂ ), bis (2-A) (8-hydroxyquinoline) (4-phenylphenol) aluminum (III) (abbreviation: BAlq), bis(8-hydroxyquinoline) zinc (II) (abbreviation: Znq), bis [2-(2- a metal complex such as benzoxazolyl)phenol]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenol]zinc(II) (abbreviation: ZnBTZ); 2-( 4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenyl)-4-phenyl-5 -(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxo Zin-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation :CO11), 2,2',2"-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(diphenyl) Heterocyclic compound having a polyazole skeleton such as thiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II); 2-[3-(dibenzothiophene-4) -yl)phenyl]dibenzo[f,h]quina Porphyrin (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quina Porphyrin (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quina Porphyrin (abbreviation: 2mCzBPDBq), 4,6-bis[3-(phenanthr-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothiophenyl) a heterocyclic compound having a diazine skeleton such as phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II); and 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: a heterocyclic compound having a pyridine skeleton such as 35DCzPPy) or 1,3,5-tris[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB). Among them, a heterocyclic compound having a diazine skeleton or a heterocyclic compound having a pyridine skeleton is preferred because it has good reliability. Especially with diazine (pyrimidine or pyrimidine) The heterocyclic compound of the skeleton has high electron transport properties and also contributes to lowering the driving voltage.

In addition, as a material having a hole transport property (a compound which is easy to receive a hole), 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-bis[N-(spiro-9,9'-biindene-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9- Phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4' -(9-phenyl-9H-indazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4"-(9-phenyl-9H-carbazol-3-yl Triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-indazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'- (1-Naphthyl)-4"-(9-phenyl-9H-indazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4 -(9-phenyl-9H-carbazol-3-yl)phenyl]nonan-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazole) -3-yl)phenyl]spiro-9,9-biindole-2-amine (abbreviation: PCBASF) a compound having an aromatic amine skeleton; 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-bis(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6 - bis(3,5-diphenylphenyl)-9-phenyloxazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), etc. a compound of the carbazole skeleton; 4,4',4"-(phenyl-1,3,5-triyl)tris(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4 -[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-茀-9- a compound having a thiophene skeleton such as phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV); and 4,4',4"-(phenyl-1,3,5-triyl) three (dibenzofuran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi a compound having a furan skeleton such as -II). Among them, a compound having an aromatic amine skeleton and a compound having a carbazole skeleton are preferable because they have good reliability and high hole transportability and contribute to lowering of a driving voltage.

Further, in addition to the above-described carrier transport material, a carrier transport material may be selected from known materials and used. Further, the formed excimer is a luminescence derived from the energy difference of the HOMO energy level on the shallow side and the LUMO energy level on the deep side of the combined compound, so that it is the first organic compound and the second organic compound. The combination and the combination of the third organic compound and the fourth organic compound select a combination of luminescence that achieves the desired luminescent wavelength. Further, one of the first organic compound and the second organic compound may be the same as one of the third organic compound and the fourth organic compound. At this time, the kind of the material constituting the light-emitting element can be reduced, thereby being advantageous in terms of cost.

Further, by using one of the above combinations as a material having electron transport properties and the other as a material having hole transportability, it is advantageous to form an exciplex. Further, by changing the content of each compound, the transportability of the light-emitting layer can be easily adjusted, and the recombination region can be easily controlled. The ratio of the content of the material having the hole transport property and the material having the electron transport property is set to a material having hole transportability: a material having electron transportability = 1:9 to 9:1.

The light-emitting layer 113 having the above configuration can be produced by co-evaporation using a vacuum deposition method, an inkjet method using a mixed solution, a spin coating method, a dip coating method, or the like.

In the present embodiment, a configuration is described in which the first light-emitting layer 113a is formed on the anode side and the second light-emitting layer 113b is formed on the cathode side. However, the stacking order may be reversed. That is, the second light-emitting layer 113b may be formed on the anode side and the first light-emitting layer 113a may be formed on the cathode side.

The structure and effect of the light-emitting layer 113 other than the above-described structure are the same as those of the first embodiment. The description of the first embodiment will be referred to.

The electron transport layer 114 is a layer containing a material having electron transport properties. For example, the electron transport layer 114 is a layer composed of a metal complex having a quinoline skeleton or a benzoquinoline skeleton, or the like: tris(8-hydroxyquinoline)aluminum (abbreviation: Alq), tris(4-methyl) -8-hydroxyquinoline)aluminum (abbreviation: Almq ₃ ), bis(10-hydroxybenzo[h]quinoline)indole (abbreviation: BeBq ₂ ), bis(2-methyl-8-hydroxyquinoline) ( 4-phenylphenolate) aluminum (abbreviation: BAlq) or the like. In addition, bis[2-(2-hydroxyphenyl)benzoxazole]zinc (abbreviation: Zn(BOX) ₂ ), bis[2-(2-hydroxyphenyl)benzothiazole] can also be used. A metal complex having an oxazole or a thiazole ligand, such as zinc (abbreviation: Zn(BTZ) ₂ ). Further, in addition to the metal complex, 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD) can also be used. , 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 3-(4-biphenyl) -4-Phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), red morpholine (abbreviation: BPhen), bath copper spirit (abbreviation: BCP), etc. . The substance described herein has high electron transport property and is a substance mainly having an electron mobility of 10 ^-6 cm ² /Vs or more. Note that the above-described electron transporting host material can also be used for the electron transport layer 114.

Further, the electron transport layer 114 may be a single layer or a laminate of two or more layers of the above-described materials.

Further, a layer that controls the movement of the electron carrier may be provided between the electron transport layer and the light-emitting layer. This is a layer obtained by adding a small amount of a substance having high electron trapping property to a material having high electron transport property as described above, and the carrier balance can be adjusted by suppressing the movement of the electron carrier. Such a structure exerts a great effect on suppressing problems occurring due to electrons passing through the light-emitting layer (for example, a decrease in the life of the element).

In addition, the electron injection layer 115 may be provided in contact with the second electrode 102 between the electron transport layer 114 and the second electrode 102. As the electron injecting layer 115, an alkali metal such as lithium fluoride (LiF), cesium fluoride (CsF) or calcium fluoride (CaF ₂ ), an alkaline earth metal or a compound thereof can be used. For example, a layer in which an alkali metal, an alkaline earth metal or a compound thereof is contained in a layer composed of a substance having electron transport property can be used. By using a layer containing an alkali metal or an alkaline earth metal in a layer composed of a substance having electron transport properties as the electron injecting layer 115, electrons can be efficiently injected from the second electrode 102, which is more preferable.

As the substance forming the second electrode 102, a metal having a small work function (specifically, 3.8 eV or less), an alloy, a conductive compound, a mixture thereof, or the like can be used. Specific examples of such a cathode material include an alkali metal such as lithium (Li) or cesium (Cs), magnesium (Mg), calcium (Ca), or strontium (Sr), which belongs to the first group of the periodic table. Or a group 2 element, an alloy containing them (MgAg, AlLi), a rare earth metal such as Eu (Eu) or Yb (Yb), an alloy containing the same, and the like. However, by providing an electron injecting layer between the second electrode 102 and the electron transporting layer, various conductive materials such as Al, Ag, ITO, indium oxide containing cerium or cerium oxide can be oxidized regardless of the magnitude of the work function. Tin or the like is used as the second electrode 102. Film formation of these conductive materials can be performed by a sputtering method, an inkjet method, a spin coating method, or the like.

Further, as a method of forming the EL layer 103, various methods can be used regardless of the dry treatment or the wet treatment. For example, a vacuum deposition method, an inkjet method, a spin coating method, or the like can also be used. Further, different film formation methods may be used depending on each electrode or each layer.

The electrode may be formed by a wet treatment such as a sol-gel method or a wet treatment using a paste of a metal material. Further, the electrode may be formed by a dry process such as a sputtering method or a vacuum deposition method.

In the light-emitting element including the above structure, a current flows due to a potential difference generated between the first electrode 101 and the second electrode 102, and the holes and electrons are in the light-emitting layer 113 which is a layer containing a substance having high luminosity. Re-knot Combine to emit light. In other words, the light emitting region is formed in the light emitting layer 113.

Light is taken out to the outside through either or both of the first electrode 101 and the second electrode 102. Therefore, either or both of the first electrode 101 and the second electrode 102 are composed of an electrode having light transmissivity. When only the first electrode 101 has light transmissivity, light is taken out through the first electrode 101. In addition, when only the second electrode 102 has light transmissivity, light is taken out through the second electrode 102. When both the first electrode 101 and the second electrode 102 have light transmissivity, light is taken out through the first electrode 101 and the second electrode 102.

Note that the structure of the layer disposed between the first electrode 101 and the second electrode 102 is not limited to the above structure. However, it is preferable to adopt a structure in which a light-emitting region in which a hole and electrons are recombined is provided in a portion far from the first electrode 101 and the second electrode 102, so as to suppress the proximity of the light-emitting region to the metal for the electrode or the carrier injection layer. And the quenching that occurs.

Further, in order to suppress energy transfer from the excitons generated in the light-emitting layer, the hole transport layer and the electron transport layer which are in contact with the light-emitting layer 113, in particular, are in contact with the side of the light-emitting layer 113 which is close to the light-emitting region. The sub-transport layer is preferably composed of a substance having a band gap larger than that of the excimer complex contained in the light-emitting layer.

The light-emitting element of the present embodiment can be fabricated on a substrate made of glass, plastic, or the like. The order of manufacturing the light-emitting elements on the substrate may be sequentially stacked from the first electrode 101 side and sequentially stacked from the second electrode 102 side. The light-emitting device may have one light-emitting element formed on one substrate or a plurality of light-emitting elements formed on one substrate. By one in A plurality of such light-emitting elements are fabricated on a plurality of substrates, and an illumination device or a passive matrix type light-emitting device in which the elements are divided can be manufactured. Further, a thin film transistor (TFT) may be formed, for example, on a substrate made of glass, plastic, or the like, and a light-emitting element may be fabricated on an electrode electrically connected to the TFT. Thereby, an active matrix type light-emitting device that controls the driving of the light-emitting elements by the TFT can be manufactured. Note that there is no particular limitation on the structure of the TFT. The TFTs may be staggered or inverted. Further, the crystallinity of the semiconductor used for the TFT is also not particularly limited, and an amorphous semiconductor or a crystalline semiconductor can be used. Further, the driving circuit formed in the TFT substrate may be composed of either an N-type or a P-type TFT, or may be composed of only one of an N-type and a P-type TFT.

This embodiment can be combined as appropriate with other embodiments.

Embodiment 3

In the present embodiment, a light-emitting device manufactured using the light-emitting elements described in the first embodiment and the second embodiment will be described.

In the present embodiment, a light-emitting device manufactured using the light-emitting elements described in the first embodiment and the second embodiment will be described with reference to FIGS. 2A and 2B. Note that FIG. 2A is a plan view showing the light-emitting device, and FIG. 2B is a cross-sectional view taken along line A-B and line C-D in FIG. 2A. The light-emitting device includes, as a unit for controlling the light emission of the light-emitting element, a drive circuit portion (source line drive circuit) 601, a pixel portion 602, and a drive circuit portion (gate line drive circuit) 603 indicated by broken lines. In addition, the component symbol 604 is a sealing substrate, and the component symbol 605 is a sealing material surrounded by the sealing material 605. The side is the space 607.

Note that the boot wiring 608 is a wiring for transmitting signals input to the source line driving circuit 601 and the gate line driving circuit 603, and receives video signals, clocks from an FPC (flexible printed circuit) 609 serving as an external input terminal. Signal, start signal, reset signal, etc. Note that although only the FPC is illustrated here, the FPC may also be mounted with a printed wiring board (PWB). The light-emitting device in the present specification includes not only the light-emitting device main body but also a light-emitting device mounted with an FPC or a PWB.

Next, the cross-sectional structure will be described with reference to Fig. 2B. Although the driver circuit portion and the pixel portion are formed on the element substrate 610, one of the source line driver circuit 601 and the pixel portion 602 as the driver circuit portion is shown here.

As the source line driving circuit 601, a CMOS circuit in which an n-channel type TFT 623 and a p-channel type TFT 624 are combined is formed. In addition, the driving circuit can also be formed using various CMOS circuits, PMOS circuits, or NMOS circuits. Further, in the present embodiment, a driver integrated type in which a drive circuit is formed on a substrate is shown, but it is not necessary to adopt this configuration, and the drive circuit may be formed outside without being formed on the substrate.

In addition, the pixel portion 602 is formed of a plurality of pixels, each of which includes a switching TFT 611, a current controlling TFT 612, and a first electrode 613 electrically connected to the drain of the current controlling TFT 612. Note that the insulator 614 is formed in such a manner as to cover the end of the first electrode 613. Here, the insulator 614 is formed using a positive photosensitive acrylic resin film.

In addition, in order to obtain good coverage, at the upper end of the insulator 614 The portion or the lower end forms a curved surface having a curvature. For example, in the case where a positive photosensitive acrylic resin is used as the material of the insulator 614, it is preferable that only the upper end portion of the insulator 614 includes a curved surface having a radius of curvature (0.2 μm to 3 μm). Further, as the insulator 614, a negative photosensitive resin or a positive photosensitive resin can be used.

An EL layer 616 and a second electrode 617 are formed on the first electrode 613. Here, it is preferred to use a material having a large work function as a material for the first electrode 613 used as an anode. For example, in addition to, for example, an ITO film, an indium tin oxide film containing germanium, an indium oxide film containing 2 wt.% to 20 wt.% of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, or the like can be used. In addition to the single layer film, a laminated film composed of a titanium nitride film and a film mainly composed of aluminum, and a film composed of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film may be used. Layer structure film and the like. Note that when a laminated structure is employed, the electric resistance as a wiring is also low, a good ohmic contact can be obtained, and the function of the anode can be further exerted.

Further, the EL layer 616 is formed by various methods such as a vapor deposition method using a vapor deposition mask, an inkjet method, and a spin coating method. The EL layer 616 includes the structures described in the first embodiment and the second embodiment. Further, as another material constituting the EL layer 616, a low molecular compound or a high molecular compound (including an oligomer or a dendrimer) may be used.

Further, as a material for the second electrode 617 formed on the EL layer 616 and serving as a cathode, it is preferable to use a material having a small work function (Al, Mg, Li, Ca, or an alloy thereof and a compound (MgAg, MgIn, AlLi, etc.), etc.). Note that when the light generated in the EL layer 616 is made When passing through the second electrode 617, it is preferable to use a metal thin film and a transparent conductive film (ITO, indium oxide containing 2 wt.% to 20 wt.% of zinc oxide, indium tin oxide containing antimony, A laminated structure composed of zinc oxide (ZnO) or the like is used as the second electrode 617.

The light emitting element is formed of a first electrode 613, an EL layer 616, and a second electrode 617. This light-emitting element is a light-emitting element having the structure described in Embodiment 1 or 2. Although a plurality of light-emitting elements are formed in the pixel portion, the light-emitting device of the present embodiment may include both the light-emitting element described in the first embodiment or the second embodiment and the light-emitting element including the other configuration.

In addition, by bonding the sealing substrate 604 to the element substrate 610 using the sealing material 605, a structure is formed in which the light emitting element 618 is mounted in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. Note that the space 607 is filled with a filler, and as the filler, a sealing material 605 is used in addition to an inert gas (nitrogen or argon or the like). It is preferable to form a concave portion in the sealing substrate and to provide the desiccant 625 therein to suppress deterioration due to moisture.

Further, it is preferable to use an epoxy resin or a glass frit as the sealing material 605. Further, these materials are preferably materials which do not allow water or oxygen to pass through as much as possible. Further, as a material for sealing the substrate 604, in addition to a glass substrate or a quartz substrate, a plastic substrate composed of FRP (glass fiber reinforced plastic), PVF (polyvinyl fluoride), polyester, acrylic resin or the like can be used. .

As described above, it is possible to obtain the use of Embodiment 1 or Embodiment 2 A light-emitting device manufactured by the described light-emitting element.

Since the light-emitting device described in Embodiment 1 or Embodiment 2 is used as the light-emitting device of the present embodiment, a light-emitting device having excellent characteristics can be obtained. Specifically, the light-emitting element described in Embodiment 1 or Embodiment 2 is a light-emitting element having excellent light-emitting efficiency, and a light-emitting device with reduced power consumption can be realized. Further, the light-emitting element described in Embodiment 1 or Embodiment 2 is a light-emitting element that can be easily manufactured, and an inexpensive light-emitting device can be provided.

3A and 3B show an example of a light-emitting device that realizes full colorization by forming a colored layer (color filter) or the like by forming a light-emitting element that exhibits white light emission. 3A illustrates a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, a pixel portion 1040, The drive circuit portion 1041, the first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting elements, the partition wall 1025, the EL layer 1028, the second electrode 1029 of the light-emitting element, the sealing substrate 1031, the sealing material 1032, and the like.

In addition, in FIG. 3A, the colored layer (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) is provided on the transparent substrate 1033. In addition, a black layer (black matrix) 1035 can also be provided. The transparent substrate 1033 provided with the colored layer and the black layer is aligned and fixed to the substrate 1001. In addition, the colored layer and the black layer are covered by the cover layer 1036. In addition, FIG. 3A shows a light-emitting layer having light transmitted through the colored layer and transmitted to the outside, and light transmitted through the color-colored layers of the respective colors and transmitted to the outside. In the layer, light that does not pass through the colored layer becomes white light, and light that has passed through the colored layer becomes red light, blue light, or green light, so that images can be presented in pixels of four colors.

FIG. 3B shows an example in which a colored layer (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) is formed between the gate insulating film 1003 and the first interlayer insulating film 1020. As described above, the colored layer may be provided between the substrate 1001 and the sealing substrate 1031.

In addition, although the light-emitting device having the structure (bottom emission type) for taking out light on the side of the substrate 1001 on which the TFT is formed has been described above, a structure (top emission type) having light emission on the side of the sealing substrate 1031 may be employed. Light emitting device. Fig. 4 is a cross-sectional view showing a top emission type light-emitting device. In this case, the substrate 1001 can use a substrate that does not transmit light. The process until the connection electrode for connecting the TFT and the anode of the light-emitting element is manufactured in the same manner as the bottom emission type light-emitting device. Then, a third interlayer insulating film 1037 is formed in such a manner as to cover the electrode 1022. The third interlayer insulating film 1037 may also have a flattening function. The third interlayer insulating film 1037 may be formed using the same material as the second interlayer insulating film or other known materials.

Although the first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting element are all anodes, they may be cathodes. Further, in the case of employing a top emission type light-emitting device as shown in FIG. 4, the first electrode is preferably a reflective electrode. The structure of the EL layer 1028 is a structure in which the EL layer 103 described in Embodiment 1 or Embodiment 2 is employed, and an element structure capable of obtaining white light emission is employed.

In the case of employing the top emission structure shown in FIG. 4, sealing can be performed using the sealing substrate 1031 provided with the colored layer (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B). The sealing substrate 1031 may also be provided with a black layer (black matrix) 1035 between the pixels and the pixels. The colored layer (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) and black layer (black matrix) may be covered by the cover layer 1036. Further, as the sealing substrate 1031, a substrate having light transmissivity is used.

Further, although an example in which full-color display is performed in four colors of red, green, blue, and white is shown here, it is not limited thereto. It can also be displayed in full color in three colors of red, green, and blue.

Since the light-emitting device described in Embodiment 1 or Embodiment 2 is used as the light-emitting device of the present embodiment, a light-emitting device having excellent characteristics can be obtained. Specifically, the light-emitting element described in Embodiment 1 or Embodiment 2 is a light-emitting element having excellent light-emitting efficiency, and a light-emitting device with reduced power consumption can be realized. Further, the light-emitting element described in Embodiment 1 or Embodiment 2 is a light-emitting element that can be easily manufactured, and an inexpensive light-emitting device can be provided.

Although the active matrix type light-emitting device has been described here, a passive matrix type light-emitting device will be described below. 5A and 5B show a passive matrix type light-emitting device manufactured by using the present invention. Note that FIG. 5A is a perspective view showing the light emitting device, and FIG. 5B is a cross-sectional view obtained by cutting FIG. 5A along the line X-Y. In FIGS. 5A and 5B, an EL layer 955 is disposed between the electrode 952 on the substrate 951 and the electrode 956. The end of the electrode 952 is absolutely The edge layer 953 covers. An isolation layer 954 is disposed on the insulating layer 953. The sidewall of the isolation layer 954 has an inclination such that the closer to the substrate surface, the narrower the spacing between the two sidewalls. In other words, the cross section of the spacer layer 954 in the short side direction is trapezoidal, the bottom side (the side which faces the same direction as the surface direction of the insulating layer 953 and is in contact with the insulating layer 953) is larger than the upper side (the direction toward the surface of the insulating layer 953) The same direction and the side not in contact with the insulating layer 953 are short. As described above, by providing the isolation layer 954, it is possible to prevent malfunction of the light-emitting element caused by static electricity or the like. Further, in the passive matrix type light-emitting device, by using the light-emitting efficiency-good light-emitting element described in the first embodiment or the second embodiment, a light-emitting device in which power consumption is reduced can be obtained. Further, the light-emitting element described in Embodiment 1 or Embodiment 2 is a light-emitting element that can be easily manufactured, and an inexpensive light-emitting device can be provided.

Since the light-emitting device described above can control each of the plurality of minute light-emitting elements arranged in a matrix, the display device that performs display of the image can be suitably used.

Further, the present embodiment can be freely combined with other embodiments.

Embodiment 4

In the present embodiment, an example in which the light-emitting element described in the first embodiment or the second embodiment is used for a lighting device will be described with reference to FIGS. 6A and 6B. Fig. 6B is a plan view of the lighting apparatus, and Fig. 6A is a cross-sectional view taken along line e-f in Fig. 6B.

In the illumination device of the present embodiment, the first electrode 401 is formed on the light-transmitting substrate 400 serving as a support. First electrode 401 phase It is the first electrode 101 in Embodiment 1. When light is taken out from the side of the first electrode 401, the first electrode 401 is formed using a material having light transmissivity.

In addition, a pad 412 for supplying a voltage to the second electrode 404 is formed on the substrate 400.

An EL layer 403 is formed on the first electrode 401. The EL layer 403 corresponds to the structure of the EL layer 103 in the first embodiment. Note that as their structures, each description is referred to.

The second electrode 404 is formed in such a manner as to cover the EL layer 403. The second electrode 404 corresponds to the second electrode 102 in the first embodiment. When light is taken out from the side of the first electrode 401, the second electrode 404 is formed using a material having a high reflectance. A voltage is supplied to the second electrode 404 by connecting the second electrode 404 to the pad 412.

As described above, the illumination device described in the present embodiment includes the light-emitting elements including the first electrode 401, the EL layer 403, and the second electrode 404. Since the light-emitting element is a light-emitting element having high luminous efficiency, the illumination device of the present embodiment can be an illumination device having a small power consumption. Further, the light-emitting element described in Embodiment 1 or Embodiment 2 is a light-emitting element that can be easily manufactured, and an inexpensive lighting device can be provided.

The light-emitting element having the above structure is fixed on the substrate 407 using the sealing materials 405, 406 to perform sealing, thereby manufacturing a lighting apparatus. It is also possible to use only one of the sealing materials 405 and 406. Further, the inner sealing material 406 (not shown in FIG. 6B) may be mixed with the desiccant, whereby moisture can be absorbed to improve reliability.

In addition, by extending to the outside of the sealing materials 405, 406 The pad 412 and a portion of the first electrode 401 are provided to be used as an external input terminal. Further, an IC chip 420 or the like to which a converter or the like is mounted may be provided on the external input terminal.

Since the illumination device according to the present embodiment includes the light-emitting element described in Embodiment 1 or Embodiment 2 in the EL element, it is possible to realize an illumination device having a small power consumption. In addition, a lighting device with a low driving voltage can be realized. Further, the light-emitting element described in Embodiment 1 or Embodiment 2 is a light-emitting element that can be easily manufactured, and an inexpensive light-emitting device can be provided.

Embodiment 5

In the present embodiment, an example of an electronic device including a light-emitting element described in Embodiment 1 or Embodiment 2 will be described. The light-emitting element described in the first embodiment or the second embodiment is a light-emitting element having good light-emitting efficiency and reduced power consumption. As a result, the electronic device according to the present embodiment can realize an electronic device including a light-emitting portion in which power consumption is reduced. Further, since the light-emitting element described in Embodiment 1 or Embodiment 2 is a light-emitting element that can be easily manufactured, an inexpensive electronic device can be provided.

Examples of the electronic device using the above-described light-emitting element include a television (also referred to as a television or a television receiver), a display for a computer, a video camera such as a digital camera, a digital camera, a digital photo frame, and a mobile phone ( Also known as mobile phones, mobile phone devices, portable game consoles, portable information terminals, audio reproduction devices, pachinko machines, and the like. Specific examples of these electronic devices are shown below.

Fig. 7A shows an example of a television set. In the television set, a display portion 7103 is incorporated in the casing 7101. In addition, the structure in which the outer casing 7101 is supported by the bracket 7105 is shown here. The display unit 7103 can be displayed by displaying the video on the display unit 7103, and the light-emitting elements described in the first embodiment and the second embodiment are arranged in a matrix. The light-emitting element can realize a light-emitting element having high luminous efficiency. In addition, the light-emitting element can realize a light-emitting element having a low driving voltage. In addition, the light-emitting element can realize a light-emitting element having a long life. Therefore, the television including the display portion 7103 composed of the light-emitting elements can realize a television set whose power consumption is reduced. In addition, the television can realize a television with a small driving voltage. In addition, the television can realize an inexpensive television set.

The operation of the television can be performed by using an operation switch provided in the casing 7101 or a separately provided remote controller 7110. By using the operation keys 7109 provided in the remote controller 7110, the channel and the volume can be controlled, whereby the image displayed on the display unit 7103 can be controlled. Further, a display unit 7107 for displaying information output from the remote controller 7110 may be provided in the remote controller 7110.

Further, the television set has a configuration including a receiver, a data machine, and the like. A general television broadcast can be received by the receiver. Furthermore, by connecting the data machine to a wired or wireless communication network, it is possible to perform one-way (from sender to receiver) or two-way (between sender and receiver or receiver) information communication. .

7B1 shows a computer including a main body 7201, a housing 7202, a display portion 7203, a keyboard 7204, an external connection 埠 7205, and a pointing Device 7206, and the like. In addition, the computer is manufactured by arranging the same light-emitting elements as those described in the first embodiment or the second embodiment in a matrix form for use in the display unit 7203. The computer in Fig. 7B1 can also be in the manner shown in Fig. 7B2. The computer shown in FIG. 7B2 is provided with a second display portion 7210 instead of the keyboard 7204 and the pointing device 7206. The second display unit 7210 is a touch screen, and can perform input by operating an input display displayed on the second display unit 7210 with a finger or a dedicated pen. Further, the second display unit 7210 can display not only the input display but also other images. In addition, the display portion 7203 may be a touch screen. Since the two screens are connected by the hinge portion, it is possible to prevent problems such as screen damage, damage, and the like from occurring when being stored or handled. In addition, the computer is manufactured by arranging the light-emitting elements described in the first embodiment and the second embodiment in a matrix and using the display portion 7203. This light-emitting element can realize a light-emitting element having good light-emitting efficiency. Therefore, a computer having the display portion 7203 including the light-emitting element can realize a computer whose power consumption is reduced. In addition, the computer can implement a cheap computer.

Fig. 7C shows a portable game machine which is constituted by two outer casings of a casing 7301 and a casing 7302, and is openably and closably connected by a connecting portion 7303. A display portion 7304 manufactured by arranging the light-emitting elements described in the first embodiment and the second embodiment in a matrix shape is incorporated in the casing 7301, and a display portion 7305 is incorporated in the casing 7302. In addition, the portable game machine shown in FIG. 7C further includes a speaker portion 7306, a storage medium insertion portion 7307, an LED lamp 7308, and an input unit (the operation key 7309, the connection terminal 7310, and the sensor 7311 (including the following factors) Functions: force, displacement, position, speed, acceleration, angular velocity, number of revolutions, distance, light, liquid, magnetism, temperature, chemicals, sound, time, hardness, electric field, current, voltage, electricity, radiation, flow, humidity , slope, vibration, odor or infrared), microphone 7312), etc. Needless to say, the configuration of the portable game machine is not limited to the above configuration, and the light-emitting elements described in the first embodiment and the second embodiment are arranged in a matrix for use in at least one or both of the display unit 7304 and the display unit 7305. The display portion to be manufactured may be used, and a configuration in which other accessory devices are appropriately provided may be employed. The portable game machine shown in FIG. 7C has the functions of reading out a program or data stored in the storage medium and displaying it on the display portion; and by wirelessly communicating with other portable game machines. Realize information sharing. In addition, the functions of the portable game machine shown in FIG. 7C are not limited thereto, and may have various functions. Since the light-emitting element for the display portion 7304 has good luminous efficiency in the above-described portable game machine including the display portion 7304, the portable game machine can realize a portable game machine in which power consumption is reduced. . In addition, since the light-emitting element for the display portion 7304 can be driven with a low driving voltage, the portable game machine can realize a portable game machine of a low driving voltage. Further, the light-emitting element described in Embodiment 1 or Embodiment 2 is a light-emitting element that can be easily manufactured, and an inexpensive portable game machine can be provided.

Fig. 7D shows an example of a mobile phone. The mobile phone includes a display portion 7402, an operation button 7403, an external connection 埠 7404, a speaker 7405, a microphone 7406, and the like incorporated in the casing 7401. Further, the mobile phone 7400 includes the hairs described in the first embodiment and the second embodiment. The display unit 7402 is manufactured by arranging the optical elements in a matrix. This light-emitting element can realize a light-emitting element having good light-emitting efficiency. In addition, the light-emitting element can realize a light-emitting element having a small driving voltage. In addition, the light-emitting element can realize a light-emitting element having a long life. Therefore, the mobile phone equipped with the display unit 7402 including the light-emitting element can realize a mobile phone having reduced power consumption. In addition, the mobile phone can realize a mobile phone with a small driving voltage. Further, the light-emitting element described in Embodiment 1 or Embodiment 2 is a light-emitting element that can be easily manufactured, and an inexpensive mobile phone can be provided.

The mobile phone shown in FIG. 7D may have a structure in which the display unit 7402 is touched with a finger or the like to input information. In this case, the display unit 7402 can be touched with a finger or the like to perform an operation of making a call or composing an e-mail or the like.

The display portion 7402 mainly has three screen modes. The first is a display mode in which the display of the image is dominant, the second is an input mode in which information such as characters is input, and the third is a display input mode in two modes of a mixed display mode and an input mode.

For example, in the case of making a call or composing an e-mail, it is possible to input a character displayed on the screen by using the character input mode in which the display unit 7402 is mainly used to input characters. In this case, it is preferable to display a keyboard or a number button in most of the screen of the display unit 7402.

Further, by providing a detecting device having a sensor for detecting the inclination such as a gyroscope and an acceleration sensor inside the mobile phone, the direction of the mobile phone (vertical or horizontal) can be determined and the screen of the display portion 7402 can be automatically performed. The switching of the display.

Further, switching of the screen mode is performed by touching the display portion 7402 or operating the operation button 7403 of the casing 7401. Alternatively, the screen mode may be switched in accordance with the type of the image displayed on the display portion 7402. For example, when the image signal displayed on the display portion is the data of the motion image, the screen mode is switched to the display mode, and when the image signal is the text data, the screen mode is switched to the input mode.

Further, when the touch operation input of the display portion 7402 is not detected for a certain period of time by detecting the signal detected by the photo sensor of the display portion 7402 in the input mode, it is also possible to perform control to change the screen mode from The input mode is switched to the display mode.

The display portion 7402 can also be used as an image sensor. For example, by touching the display portion 7402 with the palm or the finger, a palm print, a fingerprint, or the like is photographed, and personal identification can be performed. Further, by using a backlight that emits near-infrared light or a light source for sensing that emits near-infrared light in the display portion, it is also possible to take a finger vein, a palm vein, or the like.

Further, the configuration described in the present embodiment can be used in combination with the structures described in the first to fourth embodiments as appropriate.

As described above, the light-emitting device including the light-emitting elements described in the first embodiment and the second embodiment has a wide range of applications, and the light-emitting device can be used in electronic devices of various fields. By using the light-emitting elements described in the first embodiment and the second embodiment, an electronic device in which power consumption is reduced can be obtained. Further, the light-emitting element described in the first embodiment or the second embodiment is a light-emitting element that can be easily manufactured, and can provide an inexpensive electronic device. Set.

FIG. 8 shows an example of a liquid crystal display device in which the light-emitting elements described in Embodiments 1 and 2 are used for a backlight. The liquid crystal display device shown in FIG. 8 includes a casing 901, a liquid crystal layer 902, a backlight unit 903, and a casing 904, and the liquid crystal layer 902 is connected to the driver IC 905. Further, the light-emitting elements described in the first embodiment and the second embodiment are used in the backlight unit 903, and current is supplied to the backlight unit 903 via the terminal 906.

By using the light-emitting elements described in the first embodiment and the second embodiment for the backlight of the liquid crystal display device, it is possible to obtain a backlight in which the power consumption is reduced. In addition, by using the light-emitting element described in the second embodiment, it is possible to manufacture a surface-emitting illumination device and to increase the area. Thereby, the area of the backlight can be increased and the area of the liquid crystal display device can be increased. In addition, since the light-emitting device using the light-emitting element described in the second embodiment can be made thinner than a conventional light-emitting device, the thickness of the display device can be reduced.

FIG. 9 shows an example in which the light-emitting elements described in the first embodiment and the second embodiment are used for a desk lamp as an illumination device. The table lamp shown in FIG. 9 includes a casing 2001 and a light source 2002, and the lighting device described in Embodiment 4 is used as the light source 2002.

FIG. 10 shows an example in which the light-emitting elements described in the first embodiment and the second embodiment are used in the indoor lighting device 3001. Since the light-emitting elements described in the first embodiment and the second embodiment are light-emitting elements in which power consumption is reduced, it is possible to provide an illumination device in which power consumption is reduced. Further, the light-emitting elements described in the first embodiment and the second embodiment can be realized. Large area, so it can be used for large-area lighting equipment. In addition, since the thickness of the light-emitting element described in the first embodiment and the second embodiment is small, it is possible to manufacture an illumination device that is thinner.

The light-emitting elements described in Embodiments 1 and 2 can be attached to a windshield or an instrument panel of an automobile. FIG. 11 shows an embodiment in which the light-emitting element described in Embodiment 2 is used for a windshield or an instrument panel of an automobile. The display area 5000 to the display area 5005 are provided using the light-emitting elements described in the first embodiment and the second embodiment.

The display area 5000 and the display area 5001 are display devices to which the light-emitting elements described in Embodiments 1 and 2 are mounted, which are provided on the windshield of an automobile. By forming the first electrode and the second electrode using the light-transmitting electrode, the light-emitting element described in Embodiments 1 and 2 can be formed as a so-called see-through display device in which the opposite scene can be seen. If the perspective display is used, it will not obstruct the view even if it is placed on the windshield of the car. Further, in the case where a transistor or the like for driving is provided, it is preferable to use a transistor having light transmissivity, such as an organic transistor using an organic semiconductor material or a transistor using an oxide semiconductor or the like.

The display region 5002 is a display device in which the light-emitting elements described in the first embodiment and the second embodiment are mounted on the pillar portion. By displaying an image from the imaging unit provided on the vehicle compartment on the display area 5002, the field of view blocked by the pillar can be supplemented. Further, similarly, the display area 5003 provided on the instrument panel portion can supplement the dead angle of the field of view blocked by the vehicle compartment by displaying the image from the image forming unit provided outside the vehicle, thereby improving safety. By displaying an image to supplement the portion that is not seen, It is safer and simpler to confirm safety.

The display area 5004 and the display area 5005 can provide navigation information, a speedometer, a tachometer, a driving distance, a fueling amount, a gear shifting state, an air conditioner setting, and various other information. The user can change the display project and layout as appropriate. In addition, these pieces of information can also be displayed on the display area 5000 to the display area 5003. In addition, the display area 5000 to the display area 5005 can also be used as a lighting device.

The light-emitting elements described in the first embodiment and the second embodiment can realize a light-emitting element having high luminous efficiency or a light-emitting element having low power consumption. Thereby, even if a plurality of large-area screens such as the display area 5000 to the display area 5005 are provided, the load of the battery can be reduced and used comfortably. Therefore, the light-emitting device or the illumination device using the light-emitting elements described in the first embodiment and the second embodiment can be applied to an in-vehicle light-emitting device or an illumination device.

12A and 12B are an example of a flip type tablet terminal. 12A is an open state, and the tablet terminal includes a housing 9630, a display portion 9631a, a display portion 9631b, a display mode changeover switch 9034, a power switch 9035, a power saving mode changeover switch 9036, a clip 9033, and an operation switch 9038. In the tablet terminal, the light-emitting device including the light-emitting elements described in the first embodiment and the second embodiment is used for one or both of the display portion 9631a and the display portion 9631b.

In the display portion 9631a, a part thereof can be used as the touch screen area 9632a, and the material can be input by touching the displayed operation key 9637. Further, as an example, the following structure is shown: the display unit Half of the 9631a only has the function of display, and the other half has the function of a touch screen, but is not limited to this structure. It is also possible to adopt a configuration in which the entire area of the display portion 9631a has a function of a touch screen. For example, a keyboard button can be displayed on the entire surface of the display portion 9631a to be used as a touch screen, and the display portion 9631b can be used as a display screen.

Further, similarly to the display portion 9631a, the display portion 9631b may be used as a touch panel region 9632b. Further, the keyboard button can be displayed on the display portion 9631b by touching the position of the keyboard display switching button 9639 on the touch screen using a finger or a stylus pen.

In addition, touch input can be simultaneously performed on the touch screen area 9632a and the touch screen area 9632b.

Further, the display mode changeover switch 9034 can switch the display directions such as the portrait display and the landscape display, and select switching of black-and-white display or color display or the like. The power saving mode changeover switch 9036 can set the displayed brightness to the most suitable brightness based on the amount of external light used during use by the photosensor built in the tablet terminal. The tablet terminal can also be equipped with other detecting devices such as a sensor for detecting an inclination such as a photo sensor, a gyroscope, and an acceleration sensor.

12A shows an example in which the display area of the display portion 9631b is equal to the display area of the display portion 9631a. However, the present invention is not limited thereto, and the size of one display portion and the size of the other display portion may be made unequal and they may be made. The display quality is different. For example, one of the display portion 9631a and the display portion 9631b can perform high-definition display as compared with the other.

FIG. 12B is a closed state, and the tablet terminal in the present embodiment An example including a housing 9630, a solar battery 9633, a charge and discharge control circuit 9634, a battery 9635, and a DCDC converter 9636 is shown. Further, in FIG. 12B, a configuration including a battery 9635 and a DCDC converter 9636 is shown as an example of the charge and discharge control circuit 9634.

In addition, the flip-type tablet terminal can close the housing 9630 when not in use. Therefore, the display portion 9631a and the display portion 9631b can be protected, and a flat panel terminal having excellent durability and superior reliability from the viewpoint of long-term use can be provided.

In addition, the tablet terminal shown in FIG. 12A and FIG. 12B may further have the following functions: displaying various kinds of information (still images, motion pictures, text images, etc.); displaying the calendar, date, time, and the like on the display unit; The touch display input or the edited touch input is displayed on the display unit; the processing is controlled by various software (programs).

By using the solar battery 9633 mounted on the surface of the tablet terminal, power can be supplied to the touch screen, the display unit, the video signal processing unit, and the like. Note that the solar cell 9633 can be disposed on one or both sides of the outer casing 9630, and the battery 9635 can be charged efficiently.

Further, the configuration and operation of the charge and discharge control circuit 9634 shown in Fig. 12B will be described with reference to the block diagram shown in Fig. 12C. 12C shows a solar battery 9633, a battery 9635, a DCDC converter 9636, a converter 9638, switches SW1 to SW3, and a display portion 9631. The battery 9635, the DCDC converter 9636, the converter 9638, and the switches SW1 to SW3 correspond to the diagram. A charge and discharge control circuit 9634 shown in Fig. 12B.

First, when the solar cell 9633 is generated by external light, it is explained. An example of work. The power generated by the solar cell is boosted or stepped down using a DCDC converter 9636 to make it a voltage for charging the battery 9635. Then, when the display unit 9631 is operated by the electric power from the solar battery 9633, the switch SW1 is turned on, and the electric power from the solar battery 9633 is boosted or stepped down to the voltage required by the display unit 9631 by the converter 9638. Further, when the display in the display portion 9631 is not performed, the configuration in which the SW1 is turned off and the SW2 is turned on to charge the battery 9635 can be employed.

Note that the solar battery 9633 is shown as an example of the power generating unit, but the power generating unit is not limited thereto, and other power generating units such as a piezoelectric element or a thermoelectric conversion element (peltier element) may be used. Charging of the battery 9635 is performed. It is also possible to use a wireless power transmission module that wirelessly (receives) to transmit and receive power for charging, or to combine other charging units for charging, and may not include a power generating unit.

Further, as long as the display portion 9631 is provided, it is not limited to the tablet terminal having the shape shown in FIGS. 12A and 12B.

101‧‧‧First electrode

102‧‧‧second electrode

103‧‧‧EL layer

111‧‧‧ hole injection layer

112‧‧‧ hole transport layer

113‧‧‧Lighting layer

113a‧‧‧First luminescent layer

113b‧‧‧second luminescent layer

114‧‧‧Electronic transport layer

115‧‧‧Electronic injection layer

Claims (17)

A light-emitting element comprising: a first electrode; a second electrode; and an EL layer sandwiched between the first electrode and the second electrode, wherein the EL layer comprises a first light-emitting layer laminated in contact with each other And a light emitting layer of the second light emitting layer, the first light emitting layer comprising a first organic compound and a second organic compound, the second light emitting layer comprising a third organic compound and a fourth organic compound, the first organic compound and the second The organic compound forms a first exciplex and the third organic compound and the fourth organic compound form a second exciplex. A light-emitting element according to claim 1, wherein light from the first excimer and the second exciplex is obtained. The light-emitting element according to claim 1, wherein an energy difference between a single-excitation energy level and a triple-excitation energy level of at least one of the first excimer and the second excimer is Below 0.2eV. The light-emitting element according to claim 1, wherein the external quantum efficiency of the light-emitting layer is 5% or more. The light-emitting element according to claim 1, wherein at least one of the first excimer and the second excimer exhibits delayed fluorescence. A light-emitting element according to claim 1, wherein a recombination region of electrons and holes in the light-emitting layer is located at an interface between the first light-emitting layer and the second light-emitting layer. The light-emitting element according to claim 1, wherein one of the first organic compound and the second organic compound is a substance having electron transport property and the other is a substance having hole transportability, and the third organic One of the compound and the fourth organic compound is a substance having electron transport property and the other is a substance having hole transportability. The illuminating element of claim 7, wherein the first electrode functions as an anode and the second electrode functions as a cathode, the first luminescent layer is located on a side of the first electrode, and the second luminescent layer is located at the second On the electrode side, the first light-emitting layer contains much more than the second light-emitting layer containing the substance having the hole transportability, and the second light-emitting layer contains the substance having the electron transport property than the first light-emitting layer Contains much more. The light-emitting element according to claim 1, wherein the first excimer and the second excimer exhibit light having a peak at different wavelengths. A light-emitting element according to claim 1, wherein the emission spectrum of the light-emitting layer has two peaks. A light-emitting element according to claim 1, wherein one of the first organic compound and the second organic compound is the same as one of the third organic compound and the fourth organic compound. The light-emitting element according to claim 1, wherein the light-emitting layer exhibits white light emission. A light emitting module comprising: the light emitting element according to claim 1; and a unit for controlling the light emitting element. A lighting device comprising a light-emitting element according to claim 1 of the patent application. A light-emitting device comprising: a light-emitting element according to item 1 of the patent application; and a unit for controlling the light-emitting element. An electronic device comprising a light-emitting element according to claim 1 of the patent application. The light-emitting element according to claim 1, wherein in the first light-emitting layer, the first organic compound and the second organic compound are mixed, and wherein the third organic compound is in the second light-emitting layer The fourth organic compound is mixed.